docs: def _parse_throttle(self, tablename, throttle):
          """ Parse a 'throttle' statement and return a RateLimit """
          amount = []
          desc = self.describe(tablename)
          throughputs = [desc.read_throughput, desc.write_throughput]
          for value, throughput in zip(throttle[1:], throughputs):
              if value == "*":
                  amount.append(0)
              elif value[-1] == "%":
                  amount.append(throughput * float(value[:-1]) / 100.0)
              else:
                  amount.append(float(value))
          cap = Capacity(*amount)  # pylint: disable=E1120
          return RateLimit(total=cap, callback=self._on_throttle)